Reply Obj. 2: Some have thought that the species of a natural thing is a form only, and that matter is not part of the species. If that were so, matter would not enter into the definition of natural things. Therefore it must be said otherwise, that matter is twofold, common, and "signate" or individual; common, such as flesh and bone; and individual, as this flesh and these bones. The intellect therefore abstracts the species of a natural thing from the individual sensible matter, but not from the common sensible matter; for example, it abstracts the species of man from "this flesh and these bones," which do not belong to the species as such, but to the individual (Metaph. vii, Did. vi, 10), and need not be considered in the species: whereas the species of man cannot be abstracted by the intellect from "flesh and bones."

Mathematical species, however, can be abstracted by the intellect from sensible matter, not only from individual, but also from common matter; not from common intelligible matter, but only from individual matter. For sensible matter is corporeal matter as subject to sensible qualities, such as being cold or hot, hard or soft, and the like: while intelligible matter is substance as subject to quantity. Now it is manifest that quantity is in substance before other sensible qualities are. Hence quantities, such as number, dimension, and figures, which are the terminations of quantity, can be considered apart from sensible qualities; and this is to abstract them from sensible matter; but they cannot be considered without understanding the substance which is subject to the quantity; for that would be to abstract them from common intelligible matter. Yet they can be considered apart from this or that substance; for that is to abstract them from individual intelligible matter. But some things can be abstracted even from common intelligible matter, such as "being," "unity," "power," "act," and the like; all these can exist without matter, as is plain regarding immaterial things. Because Plato failed to consider the twofold kind of abstraction, as above explained (ad 1), he held that all those things which we have stated to be abstracted by the intellect, are abstract in reality.

Reply Obj. 3: Colors, as being in individual corporeal matter, have the same mode of existence as the power of sight: therefore they can impress their own image on the eye. But phantasms, since they are images of individuals, and exist in corporeal organs, have not the same mode of existence as the human intellect, and therefore have not the power of themselves to make an impression on the passive intellect. This is done by the power of the active intellect which by turning towards the phantasm produces in the passive intellect a certain likeness which represents, as to its specific conditions only, the thing reflected in the phantasm. It is thus that the intelligible species is said to be abstracted from the phantasm; not that the identical form which previously was in the phantasm is subsequently in the passive intellect, as a body transferred from one place to another.

Reply Obj. 4: Not only does the active intellect throw light on the phantasm: it does more; by its own power it abstracts the intelligible species from the phantasm. It throws light on the phantasm, because, just as the sensitive part acquires a greater power by its conjunction with the intellectual part, so by the power of the active intellect the phantasms are made more fit for the abstraction therefrom of intelligible intentions. Furthermore, the active intellect abstracts the intelligible species from the phantasm, forasmuch as by the power of the active intellect we are able to disregard the conditions of individuality, and to take into our consideration the specific nature, the image of which informs the passive intellect.

Reply Obj. 5: Our intellect both abstracts the intelligible species from the phantasms, inasmuch as it considers the natures of things in universal, and, nevertheless, understands these natures in the phantasms since it cannot understand even the things of which it abstracts the species, without turning to the phantasms, as we have said above (Q. 84, A. 7). _____

SECOND ARTICLE [I, Q. 85, Art. 2]

Whether the Intelligible Species Abstracted from the Phantasm Is Related to Our Intellect As That Which Is Understood?

Objection 1: It would seem that the intelligible species abstracted from the phantasm is related to our intellect as that which is understood. For the understood in act is in the one who understands: since the understood in act is the intellect itself in act. But nothing of what is understood is in the intellect actually understanding, save the abstracted intelligible species. Therefore this species is what is actually understood.

Obj. 2: Further, what is actually understood must be in something; else it would be nothing. But it is not in something outside the soul: for, since what is outside the soul is material, nothing therein can be actually understood. Therefore what is actually understood is in the intellect. Consequently it can be nothing else than the aforesaid intelligible species.

Obj. 3: Further, the Philosopher says (1 Peri Herm. i) that "words are signs of the passions in the soul." But words signify the things understood, for we express by word what we understand. Therefore these passions of the soul—viz. the intelligible species, are what is actually understood.

On the contrary, The intelligible species is to the intellect what the sensible image is to the sense. But the sensible image is not what is perceived, but rather that by which sense perceives. Therefore the intelligible species is not what is actually understood, but that by which the intellect understands.

I answer that, Some have asserted that our intellectual faculties know only the impression made on them; as, for example, that sense is cognizant only of the impression made on its own organ. According to this theory, the intellect understands only its own impression, namely, the intelligible species which it has received, so that this species is what is understood.

This is, however, manifestly false for two reasons. First, because the things we understand are the objects of science; therefore if what we understand is merely the intelligible species in the soul, it would follow that every science would not be concerned with objects outside the soul, but only with the intelligible species within the soul; thus, according to the teaching of the Platonists all science is about ideas, which they held to be actually understood [*Q. 84, A. 1]]. Secondly, it is untrue, because it would lead to the opinion of the ancients who maintained that "whatever seems, is true" [*Aristotle, Metaph. iii. 5, and that consequently contradictories are true simultaneously. For if the faculty knows its own impression only, it can judge of that only. Now a thing seems according to the impression made on the cognitive faculty. Consequently the cognitive faculty will always judge of its own impression as such; and so every judgment will be true: for instance, if taste perceived only its own impression, when anyone with a healthy taste perceives that honey is sweet, he would judge truly; and if anyone with a corrupt taste perceives that honey is bitter, this would be equally true; for each would judge according to the impression on his taste. Thus every opinion would be equally true; in fact, every sort of apprehension.

Therefore it must be said that the intelligible species is related to the intellect as that by which it understands: which is proved thus. There is a twofold action (Metaph. ix, Did. viii, 8), one which remains in the agent; for instance, to see and to understand; and another which passes into an external object; for instance, to heat and to cut; and each of these actions proceeds in virtue of some form. And as the form from which proceeds an act tending to something external is the likeness of the object of the action, as heat in the heater is a likeness of the thing heated; so the form from which proceeds an action remaining in the agent is the likeness of the object. Hence that by which the sight sees is the likeness of the visible thing; and the likeness of the thing understood, that is, the intelligible species, is the form by which the intellect understands. But since the intellect reflects upon itself, by such reflection it understands both its own act of intelligence, and the species by which it understands. Thus the intelligible species is that which is understood secondarily; but that which is primarily understood is the object, of which the species is the likeness. This also appears from the opinion of the ancient philosophers, who said that "like is known by like." For they said that the soul knows the earth outside itself, by the earth within itself; and so of the rest. If, therefore, we take the species of the earth instead of the earth, according to Aristotle (De Anima iii, 8), who says "that a stone is not in the soul, but only the likeness of the stone"; it follows that the soul knows external things by means of its intelligible species.

Reply Obj. 1: The thing understood is in the intellect by its own likeness; and it is in this sense that we say that the thing actually understood is the intellect in act, because the likeness of the thing understood is the form of the intellect, as the likeness of a sensible thing is the form of the sense in act. Hence it does not follow that the intelligible species abstracted is what is actually understood; but rather that it is the likeness thereof.

Reply Obj. 2: In these words "the thing actually understood" there is a double implication—the thing which is understood, and the fact that it is understood. In like manner the words "abstract universal" imply two things, the nature of a thing and its abstraction or universality. Therefore the nature itself to which it occurs to be understood, abstracted or considered as universal is only in individuals; but that it is understood, abstracted or considered as universal is in the intellect. We see something similar to this is in the senses. For the sight sees the color of the apple apart from its smell. If therefore it be asked where is the color which is seen apart from the smell, it is quite clear that the color which is seen is only in the apple: but that it be perceived apart from the smell, this is owing to the sight, forasmuch as the faculty of sight receives the likeness of color and not of smell. In like manner humanity understood is only in this or that man; but that humanity be apprehended without conditions of individuality, that is, that it be abstracted and consequently considered as universal, occurs to humanity inasmuch as it is brought under the consideration of the intellect, in which there is a likeness of the specific nature, but not of the principles of individuality.

Reply Obj. 3: There are two operations in the sensitive part. One, in regard of impression only, and thus the operation of the senses takes place by the senses being impressed by the sensible. The other is formation, inasmuch as the imagination forms for itself an image of an absent thing, or even of something never seen. Both of these operations are found in the intellect. For in the first place there is the passion of the passive intellect as informed by the intelligible species; and then the passive intellect thus informed forms a definition, or a division, or a composition, expressed by a word. Wherefore the concept conveyed by a word is its definition; and a proposition conveys the intellect's division or composition. Words do not therefore signify the intelligible species themselves; but that which the intellect forms for itself for the purpose of judging of external things. _____

THIRD ARTICLE [I, Q. 85, Art. 3]

Whether the More Universal Is First in Our Intellectual Cognition?

Objection 1: It would seem that the more universal is not first in our intellectual cognition. For what is first and more known in its own nature, is secondarily and less known in relation to ourselves. But universals come first as regards their nature, because "that is first which does not involve the existence of its correlative" (Categor. ix). Therefore the universals are secondarily known as regards our intellect.

Obj. 2: Further, the composition precedes the simple in relation to us. But universals are the more simple. Therefore they are known secondarily by us.

Obj. 3: Further, the Philosopher says (Phys. i, 1), that the object defined comes in our knowledge before the parts of its definition. But the more universal is part of the definition of the less universal, as "animal" is part of the definition of "man." Therefore the universals are secondarily known by us.

Obj. 4: Further, we know causes and principles by their effects. But universals are principles. Therefore universals are secondarily known by us.

On the contrary, "We must proceed from the universal to the singular and individual" (Phys. i, 1)

I answer that, In our knowledge there are two things to be considered. First, that intellectual knowledge in some degree arises from sensible knowledge: and, because sense has singular and individual things for its object, and intellect has the universal for its object, it follows that our knowledge of the former comes before our knowledge of the latter. Secondly, we must consider that our intellect proceeds from a state of potentiality to a state of actuality; and every power thus proceeding from potentiality to actuality comes first to an incomplete act, which is the medium between potentiality and actuality, before accomplishing the perfect act. The perfect act of the intellect is complete knowledge, when the object is distinctly and determinately known; whereas the incomplete act is imperfect knowledge, when the object is known indistinctly, and as it were confusedly. A thing thus imperfectly known, is known partly in act and partly in potentiality, and hence the Philosopher says (Phys. i, 1), that "what is manifest and certain is known to us at first confusedly; afterwards we know it by distinguishing its principles and elements." Now it is evident that to know an object that comprises many things, without proper knowledge of each thing contained in it, is to know that thing confusedly. In this way we can have knowledge not only of the universal whole, which contains parts potentially, but also of the integral whole; for each whole can be known confusedly, without its parts being known. But to know distinctly what is contained in the universal whole is to know the less common, as to "animal" indistinctly is to know it as "animal"; whereas to know "animal" distinctly is know it as "rational" or "irrational animal," that is, to know a man or a lion: therefore our intellect knows "animal" before it knows man; and the same reason holds in comparing any more universal idea with the less universal.

Moreover, as sense, like the intellect, proceeds from potentiality to act, the same order of knowledge appears in the senses. For by sense we judge of the more common before the less common, in reference both to place and time; in reference to place, when a thing is seen afar off it is seen to be a body before it is seen to be an animal; and to be an animal before it is seen to be a man, and to be a man before it seen to be Socrates or Plato; and the same is true as regards time, for a child can distinguish man from not man before he distinguishes this man from that, and therefore "children at first call men fathers, and later on distinguish each one from the others" (Phys. i, 1). The reason of this is clear: because he who knows a thing indistinctly is in a state of potentiality as regards its principle of distinction; as he who knows genus is in a state of potentiality as regards "difference." Thus it is evident that indistinct knowledge is midway between potentiality and act.

We must therefore conclude that knowledge of the singular and individual is prior, as regards us, to the knowledge of the universal; as sensible knowledge is prior to intellectual knowledge. But in both sense and intellect the knowledge of the more common precedes the knowledge of the less common.

Reply Obj. 1: The universal can be considered in two ways. First, the universal nature may be considered together with the intention of universality. And since the intention of universality—viz. the relation of one and the same to many—is due to intellectual abstraction, the universal thus considered is a secondary consideration. Hence it is said (De Anima i, 1) that the "universal animal is either nothing or something secondary." But according to Plato, who held that universals are subsistent, the universal considered thus would be prior to the particular, for the latter, according to him, are mere participations of the subsistent universals which he called ideas.

Secondly, the universal can be considered in the nature itself—for instance, animality or humanity as existing in the individual. And thus we must distinguish two orders of nature: one, by way of generation and time; and thus the imperfect and the potential come first. In this way the more common comes first in the order of nature; as appears clearly in the generation of man and animal; for "the animal is generated before man," as the Philosopher says (De Gener. Animal ii, 3). The other order is the order of perfection or of the intention of nature: for instance, act considered absolutely is naturally prior to potentiality, and the perfect to the imperfect: thus the less common comes naturally before the more common; as man comes before animal. For the intention of nature does not stop at the generation of animal but goes on to the generation of man.

Reply Obj. 2: The more common universal may be compared to the less common, as the whole, and as the part. As the whole, considering that in the more universal is potentially contained not only the less universal, but also other things, as in "animal" is contained not only "man" but also "horse." As part, considering that the less common contains in its idea not only the more common, but also more; as "man" contains not only "animal" but also "rational." Therefore "animal" in itself comes into our knowledge before "man"; but "man" comes before "animal" considered as part of the same idea.

Reply Obj. 3: A part can be known in two ways. First, absolutely considered in itself; and thus nothing prevents the parts being known before the whole, as stones are known before a house is known. Secondly as belonging to a certain whole; and thus we must needs know the whole before its parts. For we know a house vaguely before we know its different parts. So likewise principles of definition are known before the thing defined is known; otherwise the thing defined would not be known at all. But as parts of the definition they are known after. For we know man vaguely as man before we know how to distinguish all that belongs to human nature.

Reply Obj. 4: The universal, as understood with the intention of universality, is, indeed, in a way, a principle of knowledge, in so far as the intention of universality results from the mode of understanding by way of abstraction. But what is a principle of knowledge is not of necessity a principle of existence, as Plato thought: since at times we know a cause through its effect, and substance through accidents. Wherefore the universal thus considered, according to the opinion of Aristotle, is neither a principle of existence, nor a substance, as he makes clear (Metaph. vii, Did. vi, 13). But if we consider the generic or specific nature itself as existing in the singular, thus in a way it is in the nature of a formal principle in regard to the singulars: for the singular is the result of matter, while the idea of species is from the form. But the generic nature is compared to the specific nature rather after the fashion of a material principle, because the generic nature is taken from that which is material in a thing, while the idea of species is taken from that which is formal: thus the notion of animal is taken from the sensitive part, whereas the notion of man is taken from the intellectual part. Thus it is that the ultimate intention of nature is to the species and not to the individual, or the genus: because the form is the end of generation, while matter is for the sake of the form. Neither is it necessary that, as regards us, knowledge of any cause or principle should be secondary: since at times through sensible causes we become acquainted with unknown effects, and sometimes conversely. _____

FOURTH ARTICLE [I, Q. 85, Art. 4]

Whether We Can Understand Many Things at the Same Time?

Objection 1: It would seem that we can understand many things at the same time. For intellect is above time, whereas the succession of before and after belongs to time. Therefore the intellect does not understand different things in succession, but at the same time.

Obj. 2: Further, there is nothing to prevent different forms not opposed to each other from actually being in the same subject, as, for instance, color and smell are in the apple. But intelligible species are not opposed to each other. Therefore there is nothing to prevent the same intellect being in act as regards different intelligible species, and thus it can understand many things at the same time.

Obj. 3: Further, the intellect understands a whole at the same time, such as a man or a house. But a whole contains many parts. Therefore the intellect understands many things at the same time.

Obj. 4: Further, we cannot know the difference between two things unless we know both at the same time (De Anima iii, 2), and the same is to be said of any other comparison. But our intellect knows the difference and comparison between one thing and another. Therefore it knows many things at the same time.

On the contrary, It is said (Topic. ii, 10) that "understanding is of one thing only, knowledge is of many."

I answer that, The intellect can, indeed, understand many things as one, but not as many: that is to say by one but not by many intelligible species. For the mode of every action follows the form which is the principle of that action. Therefore whatever things the intellect can understand under one species, it can understand at the same time: hence it is that God sees all things at the same time, because He sees all in one, that is, in His Essence. But whatever things the intellect understands under different species, it does not understand at the same time. The reason of this is that it is impossible for one and the same subject to be perfected at the same time by many forms of one genus and diverse species, just as it is impossible for one and the same body at the same time to have different colors or different shapes. Now all intelligible species belong to one genus, because they are the perfections of one intellectual faculty: although the things which the species represent belong to different genera. Therefore it is impossible for one and the same intellect to be perfected at the same time by different intelligible species so as actually to understand different things.

Reply Obj. 1: The intellect is above that time, which is the measure of the movement of corporeal things. But the multitude itself of intelligible species causes a certain vicissitude of intelligible operations, according as one operation succeeds another. And this vicissitude is called time by Augustine, who says (Gen. ad lit. viii, 20, 22), that "God moves the spiritual creature through time."

Reply Obj. 2: Not only is it impossible for opposite forms to exist at the same time in the same subject, but neither can any forms belonging to the same genus, although they be not opposed to one another, as is clear from the examples of colors and shapes.

Reply Obj. 3: Parts can be understood in two ways. First, in a confused way, as existing in the whole, and thus they are known through the one form of the whole, and so are known together. In another way they are known distinctly: thus each is known by its species; and so they are not understood at the same time.

Reply Obj. 4: If the intellect sees the difference or comparison between one thing and another, it knows both in relation to their difference or comparison; just, as we have said above (ad 3), as it knows the parts in the whole. _____

FIFTH ARTICLE [I, Q. 85, Art. 5]

Whether Our Intellect Understands by Composition and Division?

Objection 1: It would seem that our intellect does not understand by composition and division. For composition and division are only of many; whereas the intellect cannot understand many things at the same time. Therefore it cannot understand by composition and division.

Obj. 2: Further, every composition and division implies past, present, or future time. But the intellect abstracts from time, as also from other individual conditions. Therefore the intellect does not understand by composition and division.

Obj. 3: Further, the intellect understands things by a process of assimilation to them. But composition and division are not in things, for nothing is in things but what is signified by the predicate and the subject, and which is one and the same, provided that the composition be true, for "man" is truly what "animal" is. Therefore the intellect does not act by composition and division.

On the contrary, Words signify the conceptions of the intellect, as the Philosopher says (Peri Herm. i). But in words we find composition and division, as appears in affirmative and negative propositions. Therefore the intellect acts by composition and division.

I answer that, The human intellect must of necessity understand by composition and division. For since the intellect passes from potentiality to act, it has a likeness to things which are generated, which do not attain to perfection all at once but acquire it by degrees: so likewise the human intellect does not acquire perfect knowledge by the first act of apprehension; but it first apprehends something about its object, such as its quiddity, and this is its first and proper object; and then it understands the properties, accidents, and the various relations of the essence. Thus it necessarily compares one thing with another by composition or division; and from one composition and division it proceeds to another, which is the process of reasoning.

But the angelic and the Divine intellect, like all incorruptible things, have their perfection at once from the beginning. Hence the angelic and the Divine intellect have the entire knowledge of a thing at once and perfectly; and hence also in knowing the quiddity of a thing they know at once whatever we can know by composition, division, and reasoning. Therefore the human intellect knows by composition, division and reasoning. But the Divine intellect and the angelic intellect know, indeed, composition, division, and reasoning, not by the process itself, but by understanding the simple essence.

Reply Obj. 1: Composition and division of the intellect are made by differentiating and comparing. Hence the intellect knows many things by composition and division, as by knowing the difference and comparison of things.

Reply Obj. 2: Although the intellect abstracts from the phantasms, it does not understand actually without turning to the phantasms, as we have said (A. 1; Q. 84, A. 7). And forasmuch as it turns to the phantasms, composition and division of the intellect involve time.

Reply Obj. 3: The likeness of a thing is received into the intellect according to the mode of the intellect, not according to the mode of the thing. Wherefore something on the part of the thing corresponds to the composition and division of the intellect; but it does not exist in the same way in the intellect and in the thing. For the proper object of the human intellect is the quiddity of a material thing, which comes under the action of the senses and the imagination. Now in a material thing there is a twofold composition. First, there is the composition of form with matter; and to this corresponds that composition of the intellect whereby the universal whole is predicated of its part: for the genus is derived from common matter, while the difference that completes the species is derived from the form, and the particular from individual matter. The second comparison is of accident with subject: and to this real composition corresponds that composition of the intellect, whereby accident is predicated of subject, as when we say "the man is white." Nevertheless composition of the intellect differs from composition of things; for in the latter the things are diverse, whereas composition of the intellect is a sign of the identity of the components. For the above composition of the intellect does not imply that "man" and "whiteness" are identical, but the assertion, "the man is white," means that "the man is something having whiteness": and the subject, which is a man, is identified with a subject having whiteness. It is the same with the composition of form and matter: for animal signifies that which has a sensitive nature; rational, that which has an intellectual nature; man, that which has both; and Socrates that which has all these things together with individual matter; and according to this kind of identity our intellect predicates the composition of one thing with another. _____

SIXTH ARTICLE [I, Q. 85, Art. 6]

Whether the Intellect Can Be False?

Objection 1: It would seem that the intellect can be false; for the Philosopher says (Metaph. vi, Did. v, 4) that "truth and falsehood are in the mind." But the mind and intellect are the same, as is shown above (Q. 79, A. 1). Therefore falsehood may be in the mind.

Obj. 2: Further, opinion and reasoning belong to the intellect. But falsehood exists in both. Therefore falsehood can be in the intellect.

Obj. 3: Further, sin is in the intellectual faculty. But sin involves falsehood: for "those err that work evil" (Prov. 14:22). Therefore falsehood can be in the intellect.

On the contrary, Augustine says (QQ. 83, qu. 32), that "everyone who is deceived, does not rightly understand that wherein he is deceived." And the Philosopher says (De Anima iii, 10), that "the intellect is always true."

I answer that, The Philosopher (De Anima iii, 6) compares intellect with sense on this point. For sense is not deceived in its proper object, as sight in regard to color; [unless] accidentally through some hindrance occurring to the sensile organ—for example, the taste of a fever-stricken person judges a sweet thing to be bitter, through his tongue being vitiated by ill humors. Sense, however, may be deceived as regards common sensible objects, as size or figure; when, for example, it judges the sun to be only a foot in diameter, whereas in reality it exceeds the earth in size. Much more is sense deceived concerning accidental sensible objects, as when it judges that vinegar is honey by reason of the color being the same. The reason of this is evident; for every faculty, as such, is per se directed to its proper object; and things of this kind are always the same. Hence, as long as the faculty exists, its judgment concerning its own proper object does not fail. Now the proper object of the intellect is the "quiddity" of a material thing; and hence, properly speaking, the intellect is not at fault concerning this quiddity; whereas it may go astray as regards the surroundings of the thing in its essence or quiddity, in referring one thing to another, as regards composition or division, or also in the process of reasoning. Therefore, also in regard to those propositions, which are understood, the intellect cannot err, as in the case of first principles from which arises infallible truth in the certitude of scientific conclusions.

The intellect, however, may be accidentally deceived in the quiddity of composite things, not by the defect of its organ, for the intellect is a faculty that is independent of an organ; but on the part of the composition affecting the definition, when, for instance, the definition of a thing is false in relation to something else, as the definition of a circle applied to a triangle; or when a definition is false in itself as involving the composition of things incompatible; as, for instance, to describe anything as "a rational winged animal." Hence as regards simple objects not subject to composite definitions we cannot be deceived unless, indeed, we understand nothing whatever about them, as is said Metaph. ix, Did. viii, 10.

Reply Obj. 1: The Philosopher says that falsehood is in the intellect in regard to composition and division. The same answer applies to the Second Objection concerning opinion and reasoning, and to the Third Objection, concerning the error of the sinner, who errs in the practical judgment of the appetible object. But in the absolute consideration of the quiddity of a thing, and of those things which are known thereby, the intellect is never deceived. In this sense are to be understood the authorities quoted in proof of the opposite conclusion. _____

SEVENTH ARTICLE [I, Q. 85, Art. 7]

Whether One Person Can Understand One and the Same Thing Better Than Another Can?

Objection 1: It would seem that one person cannot understand one and the same thing better than another can. For Augustine says (QQ. 83, qu. 32), "Whoever understands a thing otherwise than as it is, does not understand it at all. Hence it is clear that there is a perfect understanding, than which none other is more perfect: and therefore there are not infinite degrees of understanding a thing: nor can one person understand a thing better than another can."

Obj. 2: Further, the intellect is true in its act of understanding. But truth, being a certain equality between thought and thing, is not subject to more or less; for a thing cannot be said to be more or less equal. Therefore a thing cannot be more or less understood.

Obj. 3: Further, the intellect is the most formal of all that is in man. But different forms cause different species. Therefore if one man understands better than another, it would seem that they do not belong to the same species.

On the contrary, Experience shows that some understand more profoundly than do others; as one who carries a conclusion to its first principles and ultimate causes understands it better than the one who reduces it only to its proximate causes.

I answer that, A thing being understood more by one than by another may be taken in two senses. First, so that the word "more" be taken as determining the act of understanding as regards the thing understood; and thus, one cannot understand the same thing more than another, because to understand it otherwise than as it is, either better or worse, would entail being deceived, and such a one would not understand it, as Augustine argues (QQ. 83, qu. 32). In another sense the word "more" can be taken as determining the act of understanding on the part of him who understands; and so one may understand the same thing better than someone else, through having a greater power of understanding: just as a man may see a thing better with his bodily sight, whose power is greater, and whose sight is more perfect. The same applies to the intellect in two ways. First, as regards the intellect itself, which is more perfect. For it is plain that the better the disposition of a body, the better the soul allotted to it; which clearly appears in things of different species: and the reason thereof is that act and form are received into matter according to matter's capacity: thus because some men have bodies of better disposition, their souls have a greater power of understanding, wherefore it is said (De Anima ii, 9), that "it is to be observed that those who have soft flesh are of apt mind." Secondly, this occurs in regard to the lower powers of which the intellect has need in its operation: for those in whom the imaginative, cogitative, and memorative powers are of better disposition, are better disposed to understand.

The reply to the First Objection is clear from the above; likewise the reply to the Second, for the truth of the intellect consists in the intellect understanding a thing as it is.

Reply Obj. 3: The difference of form which is due only to the different disposition of matter, causes not a specific but only a numerical difference: for different individuals have different forms, diversified according to the difference of matter. _____

EIGHTH ARTICLE [I, Q. 85, Art. 8]

Whether the Intellect Understands the Indivisible Before the Divisible?

Objection 1: It would seem that the intellect understands the indivisible before the divisible. For the Philosopher says (Phys. i, 1) that "we understand and know from the knowledge of principles and elements." But principles are indivisible, and elements are of divisible things. Therefore the indivisible is known to us before the divisible.

Obj. 2: Further, the definition of a thing contains what is known previously, for a definition "proceeds from the first and more known," as is said Topic. vi, 4. But the indivisible is part of the definition of the divisible; as a point comes into the definition of a line; for as Euclid says, "a line is length without breadth, the extremities of which are points"; also unity comes into the definition of number, for "number is multitude measured by one," as is said Metaph. x, Did. ix, 6. Therefore our intellect understands the indivisible before the divisible.

Obj. 3: Further, "Like is known by like." But the indivisible is more like to the intellect than is the divisible; because "the intellect is simple" (De Anima iii, 4). Therefore our intellect first knows the indivisible.

On the contrary, It is said (De Anima iii, 6) that "the indivisible is expressed as a privation." But privation is known secondarily. Therefore likewise is the indivisible.

I answer that, The object of our intellect in its present state is the quiddity of a material thing, which it abstracts from the phantasms, as above stated (Q. 84, A. 7). And since that which is known first and of itself by our cognitive power is its proper object, we must consider its relationship to that quiddity in order to discover in what order the indivisible is known. Now the indivisible is threefold, as is said De Anima iii, 6. First, the continuous is indivisible, since actually it is undivided, although potentially divisible: and this indivisible is known to us before its division, which is a division into parts: because confused knowledge is prior to distinct knowledge, as we have said above (A. 3). Secondly, the indivisible is so called in relation to species, as man's reason is something indivisible. This way, also, the indivisible is understood before its division into logical parts, as we have said above (De Anima iii, 6); and again before the intellect disposes and divides by affirmation and negation. The reason of this is that both these kinds of indivisible are understood by the intellect of itself, as being its proper object. The third kind of indivisible is what is altogether indivisible, as a point and unity, which cannot be divided either actually or potentially. And this indivisible is known secondarily, through the privation of divisibility. Wherefore a point is defined by way of privation "as that which has no parts"; and in like manner the notion of "one" is that is "indivisible," as stated in Metaph. x, Did. ix, 1. And the reason of this is that this indivisible has a certain opposition to a corporeal being, the quiddity of which is the primary and proper object of the intellect.

But if our intellect understood by participation of certain separate indivisible (forms), as the Platonists maintained, it would follow that a like indivisible is understood primarily; for according to the Platonists what is first is first participated by things.

Reply Obj. 1: In the acquisition of knowledge, principles and elements are not always (known) first: for sometimes from sensible effects we arrive at the knowledge of principles and intelligible causes. But in perfect knowledge, the knowledge of effects always depends on the knowledge of principles and elements: for as the Philosopher says in the same passage: "Then do we consider that we know, when we can resolve principles into their causes."

Reply Obj. 2: A point is not included in the definition of a line in general: for it is manifest that in a line of indefinite length, and in a circular line, there is no point, save potentially. Euclid defines a finite straight line: and therefore he mentions a point in the definition, as the limit in the definition of that which is limited. Unity is the measure of number: wherefore it is included in the definition of a measured number. But it is not included in the definition of the divisible, but rather conversely.

Reply Obj. 3: The likeness through which we understand is the species of the known in the knower; therefore a thing is known first, not on account of its natural likeness to the cognitive power, but on account of the power's aptitude for the object: otherwise sight would perceive hearing rather than color. _____

QUESTION 86

WHAT OUR INTELLECT KNOWS IN MATERIAL THINGS (In Four Articles)

We now have to consider what our intellect knows in material things. Under this head there are four points of inquiry:

(1) Whether it knows singulars?

(2) Whether it knows the infinite?

(3) Whether it knows contingent things?

(4) Whether it knows future things? _____

FIRST ARTICLE [I, Q. 86, Art. 4]

Whether Our Intellect Knows Singulars?

Objection 1: It would seem that our intellect knows singulars. For whoever knows composition, knows the terms of composition. But our intellect knows this composition; "Socrates is a man": for it belongs to the intellect to form a proposition. Therefore our intellect knows this singular, Socrates.

Obj. 2: Further, the practical intellect directs to action. But action has relation to singular things. Therefore the intellect knows the singular.

Obj. 3: Further, our intellect understands itself. But in itself it is a singular, otherwise it would have no action of its own; for actions belong to singulars. Therefore our intellect knows singulars.

Obj. 4: Further, a superior power can do whatever is done by an inferior power. But sense knows the singular. Much more, therefore, can the intellect know it.

On the contrary, The Philosopher says (Phys. i, 5), that "the universal is known by reason; and the singular is known by sense."

I answer that, Our intellect cannot know the singular in material things directly and primarily. The reason of this is that the principle of singularity in material things is individual matter, whereas our intellect, as have said above (Q. 85, A. 1), understands by abstracting the intelligible species from such matter. Now what is abstracted from individual matter is the universal. Hence our intellect knows directly the universal only. But indirectly, and as it were by a kind of reflection, it can know the singular, because, as we have said above (Q. 85, A. 7), even after abstracting the intelligible species, the intellect, in order to understand, needs to turn to the phantasms in which it understands the species, as is said De Anima iii, 7. Therefore it understands the universal directly through the intelligible species, and indirectly the singular represented by the phantasm. And thus it forms the proposition "Socrates is a man." Wherefore the reply to the first objection is clear.

Reply Obj. 2: The choice of a particular thing to be done is as the conclusion of a syllogism formed by the practical intellect, as is said Ethic. vii, 3. But a singular proposition cannot be directly concluded from a universal proposition, except through the medium of a singular proposition. Therefore the universal principle of the practical intellect does not move save through the medium of the particular apprehension of the sensitive part, as is said De Anima iii, 11.

Reply Obj. 3: Intelligibility is incompatible with the singular not as such, but as material, for nothing can be understood otherwise than immaterially. Therefore if there be an immaterial singular such as the intellect, there is no reason why it should not be intelligible.

Reply Obj. 4: The higher power can do what the lower power can, but in a more eminent way. Wherefore what the sense knows materially and concretely, which is to know the singular directly, the intellect knows immaterially and in the abstract, which is to know the universal. _____

SECOND ARTICLE [I, Q. 86, Art. 2]

Whether Our Intellect Can Know the Infinite?

Objection 1: It would seem that our intellect can know the infinite. For God excels all infinite things. But our intellect can know God, as we have said above (Q. 12, A. 1). Much more, therefore, can our intellect know all other infinite things.

Obj. 2: Further, our intellect can naturally know genera and species. But there is an infinity of species in some genera, as in number, proportion, and figure. Therefore our intellect can know the infinite.

Obj. 3: Further, if one body can coexist with another in the same place, there is nothing to prevent an infinite number of bodies being in one place. But one intelligible species can exist with another in the same intellect, for many things can be habitually known at the same time. Therefore our intellect can have an habitual knowledge of an infinite number of things.

Obj. 4: Further, as the intellect is not a corporeal faculty, as we have said (Q. 76, A. 1), it appears to be an infinite power. But an infinite power has a capacity for an infinite object. Therefore our intellect can know the infinite.

On the contrary, It is said (Phys. i, 4) that "the infinite, considered as such, is unknown."

I answer that, Since a faculty and its object are proportional to each other, the intellect must be related to the infinite, as is its object, which is the quiddity of a material thing. Now in material things the infinite does not exist actually, but only potentially, in the sense of one succeeding another, as is said Phys. iii, 6. Therefore infinity is potentially in our mind through its considering successively one thing after another: because never does our intellect understand so many things, that it cannot understand more.

On the other hand, our intellect cannot understand the infinite either actually or habitually. Not actually, for our intellect cannot know actually at the same time, except what it knows through one species. But the infinite is not represented by one species, for if it were it would be something whole and complete. Consequently it cannot be understood except by a successive consideration of one part after another, as is clear from its definition (Phys. iii, 6): for the infinite is that "from which, however much we may take, there always remains something to be taken." Thus the infinite could not be known actually, unless all its parts were counted: which is impossible.

For the same reason we cannot have habitual knowledge of the infinite: because in us habitual knowledge results from actual consideration: since by understanding we acquire knowledge, as is said Ethic. ii, 1. Wherefore it would not be possible for us to have a habit of an infinity of things distinctly known, unless we had already considered the entire infinity thereof, counting them according to the succession of our knowledge: which is impossible. And therefore neither actually nor habitually can our intellect know the infinite, but only potentially as explained above.

Reply Obj. 1: As we have said above (Q. 7, A. 1), God is called infinite, because He is a form unlimited by matter; whereas in material things, the term "infinite" is applied to that which is deprived of any formal term. And form being known in itself, whereas matter cannot be known without form, it follows that the material infinite is in itself unknowable. But the formal infinite, God, is of Himself known; but He is unknown to us by reason of our feeble intellect, which in its present state has a natural aptitude for material objects only. Therefore we cannot know God in our present life except through material effects. In the future life this defect of intellect will be removed by the state of glory, when we shall be able to see the Essence of God Himself, but without being able to comprehend Him.

Reply Obj. 2: The nature of our mind is to know species abstracted from phantasms; therefore it cannot know actually or habitually species of numbers or figures that are not in the imagination, except in a general way and in their universal principles; and this is to know them potentially and confusedly.

Reply Obj. 3: If two or more bodies were in the same place, there would be no need for them to occupy the place successively, in order for the things placed to be counted according to this succession of occupation. On the other hand, the intelligible species enter into our intellect successively; since many things cannot be actually understood at the same time: and therefore there must be a definite and not an infinite number of species in our intellect.

Reply Obj. 4: As our intellect is infinite in power, so does it know the infinite. For its power is indeed infinite inasmuch as it is not terminated by corporeal matter. Moreover it can know the universal, which is abstracted from individual matter, and which consequently is not limited to one individual, but, considered in itself, extends to an infinite number of individuals. _____

THIRD ARTICLE [I, Q. 86, Art. 3]

Whether Our Intellect Can Know Contingent Things?

Objection 1: It would seem that the intellect cannot know contingent things: because, as the Philosopher says (Ethic. vi, 6), the objects of understanding, wisdom and knowledge are not contingent, but necessary things.

Obj. 2: Further, as stated in Phys. iv, 12, "what sometimes is and sometimes is not, is measured by time." Now the intellect abstracts from time, and from other material conditions. Therefore, as it is proper to a contingent thing sometime to be and sometime not to be, it seems that contingent things are not known by the intellect.

On the contrary, All knowledge is in the intellect. But some sciences are of the contingent things, as the moral sciences, the objects of which are human actions subject to free-will; and again, the natural sciences in as far as they relate to things generated and corruptible. Therefore the intellect knows contingent things.

I answer that, Contingent things can be considered in two ways; either as contingent, or as containing some element of necessity, since every contingent thing has in it something necessary: for example, that Socrates runs, is in itself contingent; but the relation of running to motion is necessary, for it is necessary that Socrates move if he runs. Now contingency arises from matter, for contingency is a potentiality to be or not to be, and potentiality belongs to matter; whereas necessity results from form, because whatever is consequent on form is of necessity in the subject. But matter is the individualizing principle: whereas the universal comes from the abstraction of the form from the particular matter. Moreover it was laid down above (A. 1) that the intellect of itself and directly has the universal for its object; while the object of sense is the singular, which in a certain way is the indirect object of the intellect, as we have said above (A. 1). Therefore the contingent, considered as such, is known directly by sense and indirectly by the intellect; while the universal and necessary principles of contingent things are known only by the intellect. Hence if we consider the objects of science in their universal principles, then all science is of necessary things. But if we consider the things themselves, thus some sciences are of necessary things, some of contingent things.

From which the replies to the objections are clear. _____

FOURTH ARTICLE [I, Q. 86, Art. 4]

Whether Our Intellect Can Know the Future?

Objection 1: It would seem that our intellect knows the future. For our intellect knows by means of intelligible species abstracted from the "here" and "now," and related indifferently to all time. But it can know the present. Therefore it can know the future.

Obj. 2: Further, man, while his senses are in suspense, can know some future things, as in sleep, and in frenzy. But the intellect is freer and more vigorous when removed from sense. Therefore the intellect of its own nature can know the future.

Obj. 3: The intellectual knowledge of man is superior to any knowledge of brutes. But some animals know the future; thus crows by their frequent cawing foretell rain. Therefore much more can the intellect know the future.

On the contrary, It is written (Eccles. 8:6, 7), "There is a great affliction for man, because he is ignorant of things past; and things to come he cannot know by any messenger."

I answer that, We must apply the same distinction to future things, as we applied above (A. 3) to contingent things. For future things considered as subject to time are singular, and the human intellect knows them by reflection only, as stated above (A. 1). But the principles of future things may be universal; and thus they may enter the domain of the intellect and become the objects of science.

Speaking, however, of the knowledge of the future in a general way, we must observe that the future may be known in two ways: either in itself, or in its cause. The future cannot be known in itself save by God alone; to Whom even that is present which in the course of events is future, forasmuch as from eternity His glance embraces the whole course of time, as we have said above when treating of God's knowledge (Q. 14, A. 13). But forasmuch as it exists in its cause, the future can be known by us also. And if, indeed, the cause be such as to have a necessary connection with its future result, then the future is known with scientific certitude, just as the astronomer foresees the future eclipse. If, however, the cause be such as to produce a certain result more frequently than not, then can the future be known more or less conjecturally, according as its cause is more or less inclined to produce the effect.

Reply Obj. 1: This argument considers that knowledge which is drawn from universal causal principles; from these the future may be known, according to the order of the effects to the cause.

Reply Obj. 2: As Augustine says (Confess. xii [*Gen. ad lit. xii. 13]), the soul has a certain power of forecasting, so that by its very nature it can know the future; hence when withdrawn from corporeal sense, and, as it were, concentrated on itself, it shares in the knowledge of the future. Such an opinion would be reasonable if we were to admit that the soul receives knowledge by participating the ideas as the Platonists maintained, because in that case the soul by its nature would know the universal causes of all effects, and would only be impeded in its knowledge by the body, and hence when withdrawn from the corporeal senses it would know the future.

But since it is connatural to our intellect to know things, not thus, but by receiving its knowledge from the senses; it is not natural for the soul to know the future when withdrawn from the senses: rather does it know the future by the impression of superior spiritual and corporeal causes; of spiritual causes, when by Divine power the human intellect is enlightened through the ministry of angels, and the phantasms are directed to the knowledge of future events; or, by the influence of demons, when the imagination is moved regarding the future known to the demons, as explained above (Q. 57, A. 3). The soul is naturally more inclined to receive these impressions of spiritual causes when it is withdrawn from the senses, as it is then nearer to the spiritual world, and freer from external distractions. The same may also come from superior corporeal causes. For it is clear that superior bodies influence inferior bodies. Hence, in consequence of the sensitive faculties being acts of corporeal organs, the influence of the heavenly bodies causes the imagination to be affected, and so, as the heavenly bodies cause many future events, the imagination receives certain images of some such events. These images are perceived more at night and while we sleep than in the daytime and while we are awake, because, as stated in De Somn. et Vigil. ii [*De Divinat. per somn. ii], "impressions made by day are evanescent. The night air is calmer, when silence reigns, hence bodily impressions are made in sleep, when slight internal movements are felt more than in wakefulness, and such movements produce in the imagination images from which the future may be foreseen."

Reply Obj. 3: Brute animals have no power above the imagination wherewith to regulate it, as man has his reason, and therefore their imagination follows entirely the influence of the heavenly bodies. Thus from such animals' movements some future things, such as rain and the like, may be known rather than from human movements directed by reason. Hence the Philosopher says (De Somn. et Vig.), that "some who are most imprudent are most far-seeing; for their intelligence is not burdened with cares, but is as it were barren and bare of all anxiety moving at the caprice of whatever is brought to bear on it." _____

QUESTION 87

HOW THE INTELLECTUAL SOUL KNOWS ITSELF AND ALL WITHIN ITSELF (In Four Articles)

We have now to consider how the intellectual soul knows itself and all within itself. Under this head there are four points of inquiry:

(1) Whether the soul knows itself by its own essence?

(2) Whether it knows its own habits?

(3) How does the intellect know its own act?

(4) How does it know the act of the will? _____

FIRST ARTICLE [I, Q. 87, Art. 1]

Whether the Intellectual Soul Knows Itself by Its Essence?

Objection 1: It would seem that the intellectual soul knows itself by its own essence. For Augustine says (De Trin. ix, 3), that "the mind knows itself, because it is incorporeal."

Obj. 2: Further, both angels and human souls belong to the genus of intellectual substance. But an angel understands itself by its own essence. Therefore likewise does the human soul.

Obj. 3: Further, "in things void of matter, the intellect and that which is understood are the same" (De Anima iii, 4). But the human mind is void of matter, not being the act of a body as stated above (Q. 76, A. 1). Therefore the intellect and its object are the same in the human mind; and therefore the human mind understands itself by its own essence.

On the contrary, It is said (De Anima iii, 4) that "the intellect understands itself in the same way as it understands other things." But it understands other things, not by their essence, but by their similitudes. Therefore it does not understand itself by its own essence.

I answer that, Everything is knowable so far as it is in act, and not, so far as it is in potentiality (Metaph. ix, Did. viii, 9): for a thing is a being, and is true, and therefore knowable, according as it is actual. This is quite clear as regards sensible things, for the eye does not see what is potentially, but what is actually colored. In like manner it is clear that the intellect, so far as it knows material things, does not know save what is in act: and hence it does not know primary matter except as proportionate to form, as is stated Phys. i, 7. Consequently immaterial substances are intelligible by their own essence according as each one is actual by its own essence.

Therefore it is that the Essence of God, the pure and perfect act, is simply and perfectly in itself intelligible; and hence God by His own Essence knows Himself, and all other things also. The angelic essence belongs, indeed, to the genus of intelligible things as act, but not as a pure act, nor as a complete act, and hence the angel's act of intelligence is not completed by his essence. For although an angel understands himself by his own essence, still he cannot understand all other things by his own essence; for he knows things other than himself by their likenesses. Now the human intellect is only a potentiality in the genus of intelligible beings, just as primary matter is a potentiality as regards sensible beings; and hence it is called "possible" [*Possibilis—elsewhere in this translation rendered "passive"—Ed.]. Therefore in its essence the human mind is potentially understanding. Hence it has in itself the power to understand, but not to be understood, except as it is made actual. For even the Platonists asserted that an order of intelligible beings existed above the order of intellects, forasmuch as the intellect understands only by participation of the intelligible; for they said that the participator is below what it participates. If, therefore, the human intellect, as the Platonists held, became actual by participating separate intelligible forms, it would understand itself by such participation of incorporeal beings. But as in this life our intellect has material and sensible things for its proper natural object, as stated above (Q. 84, A. 7), it understands itself according as it is made actual by the species abstracted from sensible things, through the light of the active intellect, which not only actuates the intelligible things themselves, but also, by their instrumentality, actuates the passive intellect. Therefore the intellect knows itself not by its essence, but by its act. This happens in two ways: In the first place, singularly, as when Socrates or Plato perceives that he has an intellectual soul because he perceives that he understands. In the second place, universally, as when we consider the nature of the human mind from knowledge of the intellectual act. It is true, however, that the judgment and force of this knowledge, whereby we know the nature of the soul, comes to us according to the derivation of our intellectual light from the Divine Truth which contains the types of all things as above stated (Q. 84, A. 5). Hence Augustine says (De Trin. ix, 6): "We gaze on the inviolable truth whence we can as perfectly as possible define, not what each man's mind is, but what it ought to be in the light of the eternal types." There is, however, a difference between these two kinds of knowledge, and it consists in this, that the mere presence of the mind suffices for the first; the mind itself being the principle of action whereby it perceives itself, and hence it is said to know itself by its own presence. But as regards the second kind of knowledge, the mere presence of the mind does not suffice, and there is further required a careful and subtle inquiry. Hence many are ignorant of the soul's nature, and many have erred about it. So Augustine says (De Trin. x, 9), concerning such mental inquiry: "Let the mind strive not to see itself as if it were absent, but to discern itself as present"—i.e. to know how it differs from other things; which is to know its essence and nature.

Reply Obj. 1: The mind knows itself by means of itself, because at length it acquires knowledge of itself, though led thereto by its own act: because it is itself that it knows, since it loves itself, as he says in the same passage. For a thing can be called self-evident in two ways, either because we can know it by nothing else except itself, as first principles are called self-evident; or because it is not accidentally knowable, as color is visible of itself, whereas substance is visible by its accident.

Reply Obj. 2: The essence of an angel is an act in the genus of intelligible things, and therefore it is both intellect and the thing understood. Hence an angel apprehends his own essence through itself: not so the human mind, which is either altogether in potentiality to intelligible things—as is the passive intellect—or is the act of intelligible things abstracted from the phantasms—as is the active intellect.

Reply Obj. 3: This saying of the Philosopher is universally true in every kind of intellect. For as sense in act is the sensible in act, by reason of the sensible likeness which is the form of sense in act, so likewise the intellect in act is the object understood in act, by reason of the likeness of the thing understood, which is the form of the intellect in act. So the human intellect, which becomes actual by the species of the object understood, is itself understood by the same species as by its own form. Now to say that in "things without matter the intellect and what is understood are the same," is equal to saying that "as regards things actually understood the intellect and what is understood are the same." For a thing is actually understood in that it is immaterial. But a distinction must be drawn: since the essences of some things are immaterial—as the separate substances called angels, each of which is understood and understands, whereas there are other things whose essences are not wholly immaterial, but only the abstract likenesses thereof. Hence the Commentator says (De Anima iii) that the proposition quoted is true only of separate substances; because in a sense it is verified in their regard, and not in regard of other substances, as already stated (Reply Obj. 2). _____

SECOND ARTICLE [I, Q. 87, Art. 2]

Whether Our Intellect Knows the Habits of the Soul by Their Essence?

Objection 1: It would seem that our intellect knows the habits of the soul by their essence. For Augustine says (De Trin. xiii, 1): "Faith is not seen in the heart wherein it abides, as the soul of a man may be seen by another from the movement of the body; but we know most certainly that it is there, and conscience proclaims its existence"; and the same principle applies to the other habits of the soul. Therefore the habits of the soul are not known by their acts, but by themselves.

Obj. 2: Further, material things outside the soul are known by their likeness being present in the soul, and are said therefore to be known by their likenesses. But the soul's habits are present by their essence in the soul. Therefore the habits of the soul are known by their essence.

Obj. 3: Further, "whatever is the cause of a thing being such is still more so." But habits and intelligible species cause things to be known by the soul. Therefore they are still more known by the soul in themselves.

On the contrary, Habits like powers are the principles of acts. But as is said (De Anima ii, 4), "acts and operations are logically prior to powers." Therefore in the same way they are prior to habits; and thus habits, like the powers, are known by their acts.

I answer that, A habit is a kind of medium between mere power and mere act. Now, it has been said (A. 1) that nothing is known but as it is actual: therefore so far as a habit fails in being a perfect act, it falls short in being of itself knowable, and can be known only by its act; thus, for example, anyone knows he has a habit from the fact that he can produce the act proper to that habit; or he may inquire into the nature and idea of the habit by considering the act. The first kind of knowledge of the habit arises from its being present, for the very fact of its presence causes the act whereby it is known. The second kind of knowledge of the habit arises from a careful inquiry, as is explained above of the mind (A. 1).

Reply Obj. 1: Although faith is not known by external movement of the body, it is perceived by the subject wherein it resides, by the interior act of the heart. For no one knows that he has faith unless he knows that he believes.

Reply Obj. 2: Habits are present in our intellect, not as its object since, in the present state of life, our intellect's object is the nature of a material thing as stated above (Q. 84, A. 7), but as that by which it understands.

Reply Obj. 3: The axiom, "whatever is the cause of a thing being such, is still more so," is true of things that are of the same order, for instance, of the same kind of cause; for example, we may say that health is desirable on account of life, and therefore life is more desirable still. But if we take things of different orders the axiom is not true: for we may say that health is caused by medicine, but it does not follow that medicine is more desirable than health, for health belongs to the order of final causes, whereas medicine belongs to the order of efficient causes. So of two things belonging essentially to the order of the objects of knowledge, the one which is the cause of the other being known, is the more known, as principles are more known than conclusions. But habit as such does not belong to the order of objects of knowledge; nor are things known on account of the habit, as on account of an object known, but as on account of a disposition or form whereby the subject knows: and therefore the argument does not prove. _____

THIRD ARTICLE [I, Q. 87, Art. 3]

Whether Our Intellect Knows Its Own Act?

Objection 1: It would seem that our intellect does not know its own act. For what is known is the object of the knowing faculty. But the act differs from the object. Therefore the intellect does not know its own act.

Obj. 2: Further, whatever is known is known by some act. If, then, the intellect knows its own act, it knows it by some act, and again it knows that act by some other act; this is to proceed indefinitely, which seems impossible.

Obj. 3: Further, the intellect has the same relation to its act as sense has to its act. But the proper sense does not feel its own act, for this belongs to the common sense, as stated De Anima iii, 2. Therefore neither does the intellect understand its own act.

On the contrary, Augustine says (De Trin. x, 11), "I understand that I understand."

I answer that, As stated above (AA. 1, 2) a thing is intelligible according as it is in act. Now the ultimate perfection of the intellect consists in its own operation: for this is not an act tending to something else in which lies the perfection of the work accomplished, as building is the perfection of the thing built; but it remains in the agent as its perfection and act, as is said Metaph. ix, Did. viii, 8. Therefore the first thing understood of the intellect is its own act of understanding. This occurs in different ways with different intellects. For there is an intellect, namely, the Divine, which is Its own act of intelligence, so that in God the understanding of His intelligence, and the understanding of His Essence, are one and the same act, because His Essence is His act of understanding. But there is another intellect, the angelic, which is not its own act of understanding, as we have said above (Q. 79, A. 1), and yet the first object of that act is the angelic essence. Wherefore although there is a logical distinction between the act whereby he understands that he understands, and that whereby he understands his essence, yet he understands both by one and the same act; because to understand his own essence is the proper perfection of his essence, and by one and the same act is a thing, together with its perfection, understood. And there is yet another, namely, the human intellect, which neither is its own act of understanding, nor is its own essence the first object of its act of understanding, for this object is the nature of a material thing. And therefore that which is first known by the human intellect is an object of this kind, and that which is known secondarily is the act by which that object is known; and through the act the intellect itself is known, the perfection of which is this act of understanding. For this reason did the Philosopher assert that objects are known before acts, and acts before powers (De Anima ii, 4).

Reply Obj. 1: The object of the intellect is something universal, namely, being and the true, in which the act also of understanding is comprised. Wherefore the intellect can understand its own act. But not primarily, since the first object of our intellect, in this state of life, is not every being and everything true, but being and true, as considered in material things, as we have said above (Q. 84, A. 7), from which it acquires knowledge of all other things.

Reply Obj. 2: The intelligent act of the human intellect is not the act and perfection of the material nature understood, as if the nature of the material thing and intelligent act could be understood by one act; just as a thing and its perfection are understood by one act. Hence the act whereby the intellect understands a stone is distinct from the act whereby it understands that it understands a stone; and so on. Nor is there any difficulty in the intellect being thus potentially infinite, as explained above (Q. 86, A. 2).

Reply Obj. 3: The proper sense feels by reason of the immutation in the material organ caused by the external sensible. A material object, however, cannot immute itself; but one is immuted by another, and therefore the act of the proper sense is perceived by the common sense. The intellect, on the contrary, does not perform the act of understanding by the material immutation of an organ; and so there is no comparison. _____

FOURTH ARTICLE [I, Q. 87, Art. 4]

Whether the Intellect Understands the Act of the Will?

Objection 1: It would seem that the intellect does not understand the act of the will. For nothing is known by the intellect, unless it be in some way present in the intellect. But the act of the will is not in the intellect; since the will and the intellect are distinct. Therefore the act of the will is not known by the intellect.

Obj. 2: Further, the act is specified by the object. But the object of the will is not the same as the object of the intellect. Therefore the act of the will is specifically distinct from the object of the intellect, and therefore the act of the will is not known by the intellect.

Obj. 3: Augustine (Confess. x, 17) says of the soul's affections that "they are known neither by images as bodies are known; nor by their presence, like the arts; but by certain notions." Now it does not seem that there can be in the soul any other notions of things but either the essences of things known or the likenesses thereof. Therefore it seems impossible for the intellect to known such affections of the soul as the acts of the will.

On the contrary, Augustine says (De Trin. x, 11), "I understand that I will."

I answer that, As stated above (Q. 59, A. 1), the act of the will is nothing but an inclination consequent on the form understood; just as the natural appetite is an inclination consequent on the natural form. Now the inclination of a thing resides in it according to its mode of existence; and hence the natural inclination resides in a natural thing naturally, and the inclination called the sensible appetite is in the sensible thing sensibly; and likewise the intelligible inclination, which is the act of the will, is in the intelligent subject intelligibly as in its principle and proper subject. Hence the Philosopher expresses himself thus (De Anima iii, 9)—that "the will is in the reason." Now whatever is intelligibly in an intelligent subject, is understood by that subject. Therefore the act of the will is understood by the intellect, both inasmuch as one knows that one wills; and inasmuch as one knows the nature of this act, and consequently, the nature of its principle which is the habit or power.

Reply Obj. 1: This argument would hold good if the will and the intellect were in different subjects, as they are distinct powers; for then whatever was in the will would not be in the intellect. But as both are rooted in the same substance of the soul, and since one is in a certain way the principle of the other, consequently what is in the will is, in a certain way, also in the intellect.

Reply Obj. 2: The "good" and the "true" which are the objects of the will and of the intellect, differ logically, but one is contained in the other, as we have said above (Q. 82, A. 4, ad 1; Q. 16, A. 4, ad 1); for the true is good and the good is true. Therefore the objects of the will fall under the intellect, and those of the intellect can fall under the will.

Reply Obj. 3: The affections of the soul are in the intellect not by similitude only, like bodies; nor by being present in their subject, as the arts; but as the thing caused is in its principle, which contains some notion of the thing caused. And so Augustine says that the soul's affections are in the memory by certain notions. _____

QUESTION 88

HOW THE HUMAN SOUL KNOWS WHAT IS ABOVE ITSELF (In Three Articles)

We must now consider how the human soul knows what is above itself, viz. immaterial substances. Under this head there are three points of inquiry:

(1) Whether the human soul in the present state of life can understand the immaterial substances called angels, in themselves?

(2) Whether it can arrive at the knowledge thereof by the knowledge of material things?

(3) Whether God is the first object of our knowledge? _____

FIRST ARTICLE [I, Q. 88, Art. 1]

Whether the Human Soul in the Present State of Life Can Understand Immaterial Substances in Themselves?

Objection 1: It would seem that the human soul in the present state of life can understand immaterial substances in themselves. For Augustine (De Trin. ix, 3) says: "As the mind itself acquires the knowledge of corporeal things by means of the corporeal senses, so it gains from itself the knowledge of incorporeal things." But these are the immaterial substances. Therefore the human mind understands immaterial substances.

Obj. 2: Further, like is known by like. But the human mind is more akin to immaterial than to material things; since its own nature is immaterial, as is clear from what we have said above (Q. 76, A. 1). Since then our mind understands material things, much more is it able to understand immaterial things.

Obj. 3: Further, the fact that objects which are in themselves most sensible are not most felt by us, comes from sense being corrupted by their very excellence. But the intellect is not subject to such a corrupting influence from its object, as is stated De Anima iii, 4. Therefore things which are in themselves in the highest degree of intelligibility, are likewise to us most intelligible. As material things, however, are intelligible only so far as we make them actually so by abstracting them from material conditions, it is clear that those substances are more intelligible in themselves whose nature is immaterial. Therefore they are much more known to us than are material things.

Obj. 4: Further, the Commentator says (Metaph. ii) that "nature would be frustrated in its end" were we unable to understand abstract substances, "because it would have made what in itself is naturally intelligible not to be understood at all." But in nature nothing is idle or purposeless. Therefore immaterial substances can be understood by us.

Obj. 5: Further, as sense is to the sensible, so is intellect to the intelligible. But our sight can see all things corporeal, whether superior and incorruptible; or lower and corruptible. Therefore our intellect can understand all intelligible substances, even the superior and immaterial.

On the contrary, It is written (Wis. 9:16): "The things that are in heaven, who shall search out?" But these substances are said to be in heaven, according to Matt. 18:10, "Their angels in heaven," etc. Therefore immaterial substances cannot be known by human investigation.

I answer that, In the opinion of Plato, immaterial substances are not only understood by us, but are the objects we understand first of all. For Plato taught that immaterial subsisting forms, which he called "Ideas," are the proper objects of our intellect, and thus first and per se understood by us; and, further, that material objects are known by the soul inasmuch as phantasy and sense are mixed up with the mind. Hence the purer the intellect is, so much the more clearly does it perceive the intelligible truth of immaterial things.

But in Aristotle's opinion, which experience corroborates, our intellect in its present state of life has a natural relationship to the natures of material things; and therefore it can only understand by turning to the phantasms, as we have said above (Q. 84, A. 7). Thus it clearly appears that immaterial substances which do not fall under sense and imagination, cannot first and per se be known by us, according to the mode of knowledge which experience proves us to have.

Nevertheless Averroes (Comment. De Anima iii) teaches that in this present life man can in the end arrive at the knowledge of separate substances by being coupled or united to some separate substance, which he calls the "active intellect," and which, being a separate substance itself, can naturally understand separate substances. Hence, when it is perfectly united to us so that by its means we are able to understand perfectly, we also shall be able to understand separate substances, as in the present life through the medium of the passive intellect united to us, we can understand material things. Now he said that the active intellect is united to us, thus. For since we understand by means of both the active intellect and intelligible objects, as, for instance, we understand conclusions by principles understood; it is clear that the active intellect must be compared to the objects understood, either as the principal agent is to the instrument, or as form to matter. For an action is ascribed to two principles in one of these two ways; to a principal agent and to an instrument, as cutting to the workman and the saw; to a form and its subject, as heating to heat and fire. In both these ways the active intellect can be compared to the intelligible object as perfection is to the perfectible, and as act is to potentiality. Now a subject is made perfect and receives its perfection at one and the same time, as the reception of what is actually visible synchronizes with the reception of light in the eye. Therefore the passive intellect receives the intelligible object and the active intellect together; and the more numerous the intelligible objects received, so much the nearer do we come to the point of perfect union between ourselves and the active intellect; so much so that when we understand all the intelligible objects, the active intellect becomes one with us, and by its instrumentality we can understand all things material and immaterial. In this he makes the ultimate happiness of man to consist. Nor, as regards the present inquiry, does it matter whether the passive intellect in that state of happiness understands separate substances by the instrumentality of the active intellect, as he himself maintains, or whether (as he says Alexander holds) the passive intellect can never understand separate substances (because according to him it is corruptible), but man understands separate substances by means of the active intellect.

This opinion, however, is untrue. First, because, supposing the active intellect to be a separate substance, we could not formally understand by its instrumentality, for the medium of an agent's formal action consists in its form and act, since every agent acts according to its actuality, as was said of the passive intellect (Q. 70, A. 1). Secondly, this opinion is untrue, because in the above explanation, the active intellect, supposing it to be a separate substance, would not be joined to us in its substance, but only in its light, as participated in things understood; and would not extend to the other acts of the active intellect so as to enable us to understand immaterial substances; just as when we see colors set off by the sun, we are not united to the substance of the sun so as to act like the sun, but its light only is united to us, that we may see the colors. Thirdly, this opinion is untrue, because granted that, as above explained, the active intellect were united to us in substance, still it is not said that it is wholly so united in regard to one intelligible object, or two; but rather in regard to all intelligible objects. But all such objects together do not equal the force of the active intellect, as it is a much greater thing to understand separate substances than to understand all material things. Hence it clearly follows that the knowledge of all material things would not make the active intellect to be so united to us as to enable us by its instrumentality to understand separate substances.

Fourthly, this opinion is untrue, because it is hardly possible for anyone in this world to understand all material things: and thus no one, or very few, could reach to perfect felicity; which is against what the Philosopher says (Ethic. i, 9), that happiness is a "kind of common good, communicable to all capable of virtue." Further, it is unreasonable that only the few of any species attain to the end of the species.

Fifthly, the Philosopher expressly says (Ethic. i, 10), that happiness is "an operation according to perfect virtue"; and after enumerating many virtues in the tenth book, he concludes (Ethic. i, 7) that ultimate happiness consisting in the knowledge of the highest things intelligible is attained through the virtue of wisdom, which in the sixth chapter he had named as the chief of speculative sciences. Hence Aristotle clearly places the ultimate felicity of man in the knowledge of separate substances, obtainable by speculative science; and not by being united to the active intellect as some imagined.

Sixthly, as was shown above (Q. 79, A. 4), the active intellect is not a separate substance; but a faculty of the soul, extending itself actively to the same objects to which the passive intellect extends receptively; because, as is stated (De Anima iii, 5), the passive intellect is "all things potentially," and the active intellect is "all things in act." Therefore both intellects, according to the present state of life, extend to material things only, which are made actually intelligible by the active intellect, and are received in the passive intellect. Hence in the present state of life we cannot understand separate immaterial substances in themselves, either by the passive or by the active intellect.

Reply Obj. 1: Augustine may be taken to mean that the knowledge of incorporeal things in the mind can be gained by the mind itself. This is so true that philosophers also say that the knowledge concerning the soul is a principle for the knowledge of separate substances. For by knowing itself, it attains to some knowledge of incorporeal substances, such as is within its compass; not that the knowledge of itself gives it a perfect and absolute knowledge of them.

Reply Obj. 2: The likeness of nature is not a sufficient cause of knowledge; otherwise what Empedocles said would be true—that the soul needs to have the nature of all in order to know all. But knowledge requires that the likeness of the thing known be in the knower, as a kind of form thereof. Now our passive intellect, in the present state of life, is such that it can be informed with similitudes abstracted from phantasms: and therefore it knows material things rather than immaterial substances.

Reply Obj. 3: There must needs be some proportion between the object and the faculty of knowledge; such as of the active to the passive, and of perfection to the perfectible. Hence that sensible objects of great power are not grasped by the senses, is due not merely to the fact that they corrupt the organ, but also to their being improportionate to the sensitive power. And thus it is that immaterial substances are improportionate to our intellect, in our present state of life, so that it cannot understand them.

Reply Obj. 4: This argument of the Commentator fails in several ways. First, because if separate substances are not understood by us, it does not follow that they are not understood by any intellect; for they are understood by themselves, and by one another.

Secondly, to be understood by us is not the end of separate substances: while only that is vain and purposeless, which fails to attain its end. It does not follow, therefore, that immaterial substances are purposeless, even if they are not understood by us at all.

Reply Obj. 5: Sense knows bodies, whether superior or inferior, in the same way, that is, by the sensible acting on the organ. But we do not understand material and immaterial substances in the same way. The former we understand by a process of abstraction, which is impossible in the case of the latter, for there are no phantasms of what is immaterial. _____

SECOND ARTICLE [I, Q. 88, Art. 2]

Whether Our Intellect Can Understand Immaterial Substances Through Its Knowledge of Material Things?

Objection 1: It would seem that our intellect can know immaterial substances through the knowledge of material things. For Dionysius says (Coel. Hier. i) that "the human mind cannot be raised up to immaterial contemplation of the heavenly hierarchies, unless it is led thereto by material guidance according to its own nature." Therefore we can be led by material things to know immaterial substances.

Obj. 2: Further, science resides in the intellect. But there are sciences and definitions of immaterial substances; for Damascene defines an angel (De Fide Orth. ii, 3); and we find angels treated of both in theology and philosophy. Therefore immaterial substances can be understood by us.

Obj. 3: Further, the human soul belongs to the genus of immaterial substances. But it can be understood by us through its act by which it understands material things. Therefore also other material substances can be understood by us, through their material effects.

Obj. 4: Further, the only cause which cannot be comprehended through its effects is that which is infinitely distant from them, and this belongs to God alone. Therefore other created immaterial substances can be understood by us through material things.

On the contrary, Dionysius says (Div. Nom. i) that "intelligible things cannot be understood through sensible things, nor composite things through simple, nor incorporeal through corporeal."

I answer that, Averroes says (De Anima iii) that a philosopher named Avempace [*Ibn-Badja, Arabian Philosopher; ob. 1183] taught that by the understanding of natural substances we can be led, according to true philosophical principles, to the knowledge of immaterial substances. For since the nature of our intellect is to abstract the quiddity of material things from matter, anything material residing in that abstracted quiddity can again be made subject to abstraction; and as the process of abstraction cannot go on forever, it must arrive at length at some immaterial quiddity, absolutely without matter; and this would be the understanding of immaterial substance.

Now this opinion would be true, were immaterial substances the forms and species of these material things; as the Platonists supposed. But supposing, on the contrary, that immaterial substances differ altogether from the quiddity of material things, it follows that however much our intellect abstract the quiddity of material things from matter, it could never arrive at anything akin to immaterial substance. Therefore we are not able perfectly to understand immaterial substances through material substances.

Reply Obj. 1: From material things we can rise to some kind of knowledge of immaterial things, but not to the perfect knowledge thereof; for there is no proper and adequate proportion between material and immaterial things, and the likenesses drawn from material things for the understanding of immaterial things are very dissimilar therefrom, as Dionysius says (Coel. Hier. ii).